Harvard and Cambridge officials scrambled yesterday to find clues to the identity of a vomiting epidemic that mysteriously struck hundreds of students Tuesday night.

University Health Services (UHS) director David S. Rosenthal '59 said yesterday that more than 150 students were admitted to the health service Tuesday night. A handful of undergraduates came to UHS with similar flu-like symptoms yesterday, but Harvard officials said that all but a small group of students were feeling better and had returned to their regular schedules.

In a clear sign of the seriousness of the problem, the Centers for Disease Control (CDC), a U.S. government run unit in Atlanta, confirmed late yesterday that one of its scientists would fly to Cambridge to investigate. The scientist will begin his probe tomorrow, according to a spokesperson for the state department of public health.

Doctors and nurses at the University Health Services had told students admitted there Tuesday night that they were likely suffering from food poisoning. But UHS director Rosenthal backed away from that assessment during a conference call with two other Harvard administrators and a Crimson reporter yesterday.

Instead, Rosenthal and other Harvard officials pointed to a similar at outbreak at Dartmouth last weekend as a possible explanation for the epidemic.

Starting Friday at 2 p.m. and continuing through Saturday, approximately 100 Dartmouth students began vomiting, and several were hospitalized, according to Alex Huppe, news director at the Hanover, N.H. school, Dartmouth officials have not been able to determine a cause of the outbreak, though a virus is believed to be the culprit.

Joe Wrinn, director of the Harvard news office, said University officials had studied recent athletic department schedules in an effort to determine any recent times when Dartmouth and Harvard students had met.

"[The epidemic] is very similar to what happened at Dartmouth," Rosenthal said. "The symptoms are strikingly similar, which points to the fact it may be a virus."

The epidemic made for a macabre scene in the lobby of the UHS urgent care entrance under Holyoke Center Tuesday night. Several students were slumped on couches with pink plastic basins placed next to them to catch their vomit. Others were collapsed on the floor, barely appearing to breathe.

The ill were mostly first-years but also included students from both the Quad and the river houses.

Harvard officials began interviews with the sick yesterday, and written surveys were also being sent to proctors for dissemination. Administrators said they would question unaffected undergraduates in an attempt to establish a "control group."

So far, interviews by both Harvard and The Crimson have turned up little evidence of food poisoning.

"There's no common food they ate," said a relieved if puzzled Berry, who said yesterday afternoon that he had already talked to a number of students himself. "We also haven't been able to find a common room they've all been in."

Berry said the dining services' strong safety record, including a perfect evaluation at its School of Public Health facility on Tuesday, made food poisoning seem less likely.

Asked if food poisoning was no longer being considered as a possible cause of the epidemic, Berry said it was too early to rule anything out.

As of late yesterday afternoon, 33 students remained at UHS, some of whom were receiving fluids intravenously. Acting President Albert Carnesale visited these undergraduates and also met with Rosenthal, Berry and other officials to discuss the situation, sources said.